A chemical, biological, radiological, nuclear or explosives (“CBRNE”) attack can have a devastating effect on a civilian population. The best response requires the earliest possible detection of the attack so that individuals can flee and civil defense authorities can contain its effects. To this end, CBRNE detection systems are being developed for deployment in urban centers.
Accurately detecting the presence of CBRNE agents that have been released in a public environment is a challenging task. A variety of factors can hamper detection and lead to false alarms. These factors include: background fluctuations in a property being monitored (e.g., particulate size, etc.), the presences of interferants, differing temperature and humidity conditions, low signal-to-noise ratio of a detector, and detector malfunctions, among others.
The public will have little tolerance for false alarms, especially those that result in significant inconvenience, such as the disruption of mass transit facilities during rush hour. If the false alarms were to occur with regularity, a “boy-who-called-wolf” attitude could rapidly develop; that is, the public would soon learn to ignore the alarms.
One way to reduce the incidence of false alarms would be to decrease detector sensitivity. But this is not a workable solution because however inconvenient a false alarm might be, an undetected attack, as might result from intentionally decreasing detector sensitivity, is far worse.
The challenge, therefore, is to develop CBRNE detection systems that, relative to the prior art, provide an increased Probability of Detection (“PoD”) and a decreased Probability of False Alarms (“PFA”).